The invention relates to a device for removing a thread. The invention also relates to a weaving machine.
2. Description of the Related Art
A jet weaving machine which includes a device for removing an improperly picked weft thread is known. The device is mounted at the inlet side of the shed between the machine's main inserting nozzle and profiled reed, outside the weft path. The device consists of a winding unit formed of winding and rotary members coaxially mounted in a tubular case. The winding member is rotatably mounted and slides axially on a bar within a sliding bearing. The rotary member is rotatably mounted in ball bearings and is driven through gears by a motor.
A free end of the winding member is provided with a circumferential conical winding surface. The rotary member has a conical recess and a rotary shaft The shape of the conical winding surface of the winding member corresponds to the shape of the conical recess of the rotary member.
The conical recess of the rotary member communicates with an ejecting channel within the rotary member's shaft. The ejecting channel opens into a waste box. A nozzle is centrally located within the winding member and is directed toward the ejecting channel. The nozzle is connected to a bushing for distributing pressurized fluid.
The winding and rotary members face each other within the tubular case. A suitable gap separates the winding and rotary members. The winding and rotary members are both axially aligned with the longitudinal axis of the weft inserting nozzle. A guiding tube is mounted transversely to the case. The guiding tube opens into the case at a position corresponding to the gap between the winding and rotary members. A guiding nozzle is mounted against the orifice of the guiding tube outside the weft path such that the weft path is situated therebetween.
To withdraw an improperly picked weft from the shed, weft is fed from the inserting nozzle and blown by the guiding nozzle into the guiding tube and, by means of the nozzle in the winding member, into the ejecting channel of the rotary member. Thereafter, weft feeding from the inserting nozzle is stopped and an auxiliary cutter (situated between the nozzle and the guiding tube) separates the weft. The winding member is then displaced toward the rotary member until the conical surfaces contact each other. The motor then begins to rotate the rotary member through the gearing such that the rotary member rotates the winding member (which is in contact therewith). As a result, the improperly picked weft is wound onto the conical surface of the winding member and is withdrawn from the shed back toward the main nozzle in a single length.
After the improperly picked weft is wound onto the conical surface of the winding member, the fuzz ball thus created is blown by the nozzle of the winding member through the ejecting channel and into the waste box.
The above-described device for removing an improperly picked weft is disadvantageous because of its positioning at the inlet to the shed. To weave under constant conditions, the device must be positioned outside the weft path, thus complicating the drawing-in of the thread into the winding unit.
Moreover, the thread is drawn back directly in a single length without first being released from the interlacing point of the fabric. Thus, particularly with delicate yarns, there exists the danger of surpassing the limiting stress of the thread, causing the weft to break before being completely withdrawn. This danger is enhanced because the weft rubs excessively against an edge of the guiding tube as it changes direction through the guide tube while being withdrawn.
Moreover, the rigid mechanical gearing of the winding unit cannot compensate for increased tensile stress in the weft caused, e.g., when the thread is locally trapped. This also causes the improperly picked weft to break. Thus, the means for driving the rotary member increases the exacting character of the prior art design.
Moreover, the position of the ejecting nozzle within the winding member is inefficient because pressurized fluid acts initially only upon the free end of the improperly picked weft. This can cause the winds of the fuzz ball to tighten on the conical surface of the winding member such that the wound up weft fuzz ball cannot be transported into the waste box.